CN202396088U

CN202396088U - Metal core printed circuit board (MCPCB) with high heat conductivity

Info

Publication number: CN202396088U
Application number: CN2011204617445U
Authority: CN
Inventors: 葛豫卿
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-11-20
Filing date: 2011-11-20
Publication date: 2012-08-22
Anticipated expiration: 2021-11-20

Abstract

The utility model relates to a metal core printed circuit board (MCPCB) with high heat conductivity and a thermal channel filled with soldering tin. The MCPCB comprises a single-side printed circuit board, a metal substrate, an adhesive binding layer for binding the circuit board with the metal substrate as a whole, and at least one thermal channel filled with soldering tin and running through the single-side printed circuit board and the adhesive binding layer. As a bottleneck part, namely, an insulating layer, in a heat transfer path of the exiting MCPCB is removed, the MCPCB provided by the utility model is greatly improved in longitudinal thermal conductivity in comparison with the existing MCPCB as the metal substrate is directly bounded with the heat dissipation part of an electronic device on the surface of the circuit board by the soldering tin with a thermal conductivity much higher than that of an insulation medium. Accordingly, the MCPCB provided by the utility model can solve the problem of large longitudinal thermal resistance of the MCPCB during application of the existing high-power light emitting diodes (LED), and is particularly suitable for LED with single package power of 5W or above.

Description

A kind of high-thermal conductive metal base printed circuit board

Technical field

The utility model relates to a kind of metal base printed circuit board that promotes the especially vertical thermal conductivity of heat transfer efficiency and preparation method thereof; Mainly solve the existing excessive problem of the vertical thermal resistance of metal base printed circuit board in High Power LED (LED) application process, be particularly useful for the LED of single package power more than 5W.

Background technology

LED is used widely at lighting field at present, and single the above LED of 3W generally can adopt metal base printed circuit board (MCPCB) as circuit and heat-radiating substrate.Existing MCPCB is owing to adopt metal substrate (being generally copper base or aluminium base), and the common FR4 printed circuit board (PCB) (PCB) that the following LED of 1W adopted before thermal conductivity was compared has had bigger lifting.Yet, although aluminium base even copper base have good thermal conductivity, can reach 205W/mK and 380W/mK respectively, because the needs of electric insulation and preparation technology's restriction all have a layer insulating between present MCPCB circuit layer and the metal substrate.The thermal conductivity of this insulating barrier has only about 0.2～2.0W/mK, causes vertical thermal conductivity of existing MCPCB to have only 1～4W/mK, looks the material that adopts insulating barrier.Along with improving constantly of present LED package level; Large size chip (Large-scale Chip) and multicore sheet (Multi Chip) encapsulation are more and more; Power consumption is increasingly high; Carrier substrate has been proposed higher heat radiation requirement, and many problems have appearred in existing MCPCB in application, and a wherein topmost reason is exactly because the insufficient LED that causes of heat radiation lost efficacy.

LED as can not in time heat being distributed, will cause LED joint temperature too high in use because 70～90% energy consumption can be converted into heat energy, causes luminous efficiency to descend, and reduces the LED life-span, more possibly directly burn chip when serious.LED is because the restriction of encapsulating structure, and front end generally adopts the materials such as epoxy resin, plastics or glass of high transmission rate for printing opacity, and thermal conductivity is all lower.Particularly when using the encapsulation of plastic lens or cover glass; In order to protect the direct brilliant line of LED wafer and base plate for packaging; Plastic lens or cover glass directly do not contact with the LED wafer but reserve certain gap; Therefore during LED used, heat was few from the ratio that front end distributes, and the heat more than 90% all need reach radiator from LED base plate for packaging back via circuit board with heat conducting mode at last.In the application, LED generally need be welded and on circuit board, supply power, and heat also need penetrate the radiating element that circuit board could arrive its back side.Therefore, the quality of the heat radiation of LED mainly can be considered from three ranks: the one, and the package level heat radiation depends primarily on the height of LED packaging thermal resistance; The 2nd, the plate heat radiation depends primarily on vertical capacity of heat transmission and the lateral heat diffusion ability of MCPCB; The 3rd, system-level heat radiation depends primarily on the structure and layout of whole outside cooling system.Because vertical thermal conductivity of existing MCPCB is lower; Become the bottleneck of high-capacity LED entire heat dissipation path; So the utility model mainly concentrates on the heat radiation of plate level, solve the existing excessive problem of metal base printed circuit board thermal resistance, significantly improve vertical thermal conductivity of metal base printed circuit board.

Summary of the invention

The utility model is primarily aimed at the existing still lower problem of the vertical thermal conductivity of MCPCB, through punching the bottleneck (insulating barrier) of heat passage part, fills the good scolding tin of heat conductivility, promotes vertical thermal conductivity of metal base printed circuit board.Because removed the metal copper foil insulating barrier two layer medium that especially thermal conductivity is extremely low at heat passage position, the heat-transfer path of whole M CPCB becomes " soldering layer-metal substrate " by original " metal copper foil-insulating barrier-metal substrate ".Because scolding tin heat conduction thermal conductivity is 50～150W/mK, exceed tens of times than the insulation material, vertical thermal conductivity that can have MCPCB now has significantly lifting.

The utility model high-thermal conductive metal base printed circuit board mainly constitutes by three layers: printed circuit board (PCB), metal substrate and the tack coat that connects printed circuit board (PCB) and metal substrate.The material of metal substrate is the thermal conductivity good metal, like copper, aluminium or copper alloy, aluminium alloy.Tack coat is epoxy jelly membrane, epoxy glass cloth bonding sheet or other resistant to elevated temperatures binding materials, can allow when follow-up LED surface soldered broken ring adhesion properties in the reflow soldering hot environment.Printed circuit board (PCB) has three-decker at least again: at least one deck circuit layer, the insulating barrier of fitting with metal substrate and be exposed to outside resistance weldering protective layer.Have a heat through-hole at least at the heat passage position of printed circuit board (PCB) and tack coat, inside has soldering to fill, and contacts seam with metallic substrate surfaces.In heat through-hole edge, leave a circle Copper Foil on the circuit layer, can be wetting by soldering flux; May command soldering flux liquid level is raised or sunken under surface tension effects; As long as thereby insert the scolding tin of appropriate amount, can make scolding tin fill surperficial flat attitude, concordant with circuit layer.The circuit pin can more be connected with the Copper Foil of heat through-hole edge according to electric needs or insulate disconnection.Because scolding tin is filled upper surface and can directly be fitted through soldering with LED heat radiation position, and lower surface directly contacts with metal substrate, formation is complete to be the heat passage of the good soldering alloy formation of thermal conductivity.Reach metal substrate efficiently thereby the caloric value of LED can see through scolding tin, through the good thermal conductivity of metal substrate to around horizontal proliferation, the radiating element of passing to the back side then dissipates.Compare with existing metal base printed circuit board, owing to removed the extremely low insulating layer material of thermal conductivity in the hot path, its vertical thermal conductivity can obtain tens hundreds of times and promote.

Description of drawings

Fig. 1 is the stratiform schematic cross-section of an embodiment of the utility model

Fig. 2 is that the utility model control scolding tin is filled the surface topography sketch map

Fig. 3 is the schematic cross-section with multilayer circuit of an embodiment of the utility model

Fig. 4 is embodiment of the utility model and LED applying sketch map

Fig. 5 is the circuit board perspective view consistent with metal substrate of an embodiment of the utility model

Fig. 6 is the Rigid Flex perspective view of an embodiment of the utility model

Fig. 7 is the layer structure sketch map of existing MCPCB

Embodiment

Below in conjunction with embodiment and accompanying drawing the utility model is done further explain, but the utility model requires the scope of protection to be not limited to the scope that embodiment representes.Under the situation that does not break away from the utility model scope, can make the change of structure and others and as other embodiment, the various aspects of each embodiment and each different embodiment thereof can make up use in any suitable manner to it.So, accompanying drawing with detail will be counted as in essence descriptive and nonrestrictive.

Fig. 1 is the stratiform schematic cross-section of an embodiment of the utility model high-thermal conductive metal base printed circuit board.This metal base printed circuit plate mainly constitutes by three layers: printed circuit board (PCB) 101, metal substrate 102 and the tack coat 103 that connects printed circuit board (PCB) 101 and metal substrate 102.The material of metal substrate 102 is the thermal conductivity good metal, like copper, aluminium or copper alloy, aluminium alloy.Tack coat 103 is epoxy jelly membrane, epoxy glass cloth bonding sheet or other resistant to elevated temperatures binding materials, can allow when follow-up LED surface soldered broken ring adhesion properties in the reflow soldering hot environment.Printed circuit board (PCB) 101 has three-decker at least again: at least one deck circuit layer 1011, the insulating barrier 1012 of fitting with metal substrate 102 and be exposed to outside resistance weldering protective layer 1013.There is through hole 104 at heat passage position at printed circuit board (PCB) 101 and tack coat 103, and through hole 104 inside are filled with scolding tin 105, contacts seam with metal substrate 102 surfaces.Scolding tin 105 can be alloys such as Sn/Cu, Sn/Ag, Sn/Bi, Sn/Ag/Cu, Sn/Ag/Bi, Sn/Cu/Bi, Sn/Cu/Ni.In through hole 104 edges, circuit layer 1011 leaves a circle Copper Foil 1014, can be wetting by soldering flux; May command soldering flux liquid level is raised or sunken under surface tension effects; As long as thereby insert the scolding tin of appropriate amount, can make scolding tin 105 surperficial flat attitudes, and concordant with circuit layer 1011.The blank well 1017 that the circuit pin 1015 of circuit layer 1011 sees through on the resistance weldering protective layer 1013 links to each other with the LED electrode.Circuit pin 1015 can more be connected with the Copper Foil 1014 of through hole 104 edges according to electric needs or insulate disconnection.Because scolding tin 105 upper surfaces can be directly fitted through soldering with LED heat radiation position, and lower surface directly contacts with metal substrate 102, formation is complete to be the heat passage of the good soldering alloy formation of thermal conductivity.The caloric value of LED can see through scolding tin 105 reach metal substrate 102 efficiently, through the good thermal conductivity of metal substrate 102 to around horizontal proliferation, the radiating element of passing to the back side then dissipates.Compare with existing metal base printed circuit board, owing to do not had the extremely low insulating layer material of thermal conductivity in the hot path, its vertical thermal conductivity can obtain tens hundreds of times and promote.

Fig. 2 fills the surface topography sketch map for the utility model control soldering.Metal substrate 102 materials are copper or surface treated aluminium, and its surface can be wetting by tin melt, thus tin liquor 205 bottom surfaces can with the intact physics seam of metal substrate 102, form good thermal interface.Because in through hole 104 edges, circuit layer 1011 leaves a circle Copper Foil 1014, also can be wetting by tin liquor 205, under wetting action, tin liquor 205 can rise to Copper Foil 1014 topmost edges.At this moment, different tin liquor amounts can cause different liquid level forms under surface tension effects: if the tin liquor 205 of filling is excessive, liquid level is protruding form 2051; If tin liquor 205 deficiencies of filling, liquid level are depression form 2052; If the tin liquor 205 of filling is just an amount of, then can form smooth liquid level 2053, can guarantee then after the curing that the surface is filled in soldering and circuit layer 1011 maintains an equal level.If in through hole 104 edges; Circuit layer 1011 is not reserved a circle Copper Foil 1014, and then through hole 104 surfaces can't be wetting with tin liquor 205, and tin liquor 205 can upwards not climbed; Only can be adsorbed in metal substrate 102 surfaces; So no matter tin liquor 205 is measured many or is measured and lack, and all can only present convex surfaces, is unfavorable for SMT technology.

Fig. 3 is another embodiment of the utility model, has the stratiform schematic cross-section of the high-thermal conductive metal base printed circuit board of multilayer circuit.Form by three parts equally: printed circuit board (PCB) 101, metal substrate 102 and the tack coat 103 that connects printed circuit board (PCB) 101 and metal substrate 102.Be that with the difference of a last embodiment this printed circuit board (PCB) 101 is double-layer printing circuit board, has two-tier circuit layer 1011 and insulating barrier 1012.Through hole 304 runs through all layers of tack coat 103 and printed circuit board (PCB) 101.All circuit must keep open circuit with through hole 304, are cut off by dielectric 1016.In through hole 304 inside scolding tin 305 is arranged, contact seam with metal substrate 102 surfaces.In through hole 304 edges; Top layer circuit layer 3011 leaves a circle Copper Foil 3014; Can be wetting by soldering flux, the same scolding tin that only need insert appropriate amount, control soldering flux liquid level is raised or sunken under surface tension effects; Make scolding tin 305 surperficial flat attitudes, and concordant with top layer circuit layer 3011 upper surfaces.The rest may be inferred, and the printed circuit board (PCB) of the utility model metal substrate penetration heat path can be more multilayer board, directly contacts with LED through scolding tin 305 because heat-transfer path is a metal substrate 102, therefore can keep good heat-conducting equally.

Fig. 4 is the sketch map after the utility model high-thermal conductive metal base printed circuit board and LED fit.Printed circuit board (PCB) 101 is fixedly connected LED 401 through soldering layer 402, and in via regions, new soldering layer 402 is filled fusion with original soldering and formed final scolding tin 405.Thereby LED 401 back heat dissipation region link to each other with metal substrate 102 through scolding tin 405, form the hot path that is made up of the heat conduction good metal entirely, and thermal conductivity improves greatly.Thereby the heat that LED 401 distributes can pass to metal substrate 102 through scolding tin 405 apace, then via metal substrate 102 to the back vertically transmit and to around horizontal proliferation.

Fig. 5 is the circuit board of an embodiment of the utility model and the sketch map of external circuit Pin locations.Circuit board 101 can adopt rigidity FR4 printed circuit board (PCB), also can adopt flexible electric circuit board, with the printed circuit board (PCB) of metal substrate 102 pressures and formation metal substrate penetration heat path.In this embodiment, circuit board 101 is in full accord with metal substrate 102 overall dimensions, and external circuit pin 501 all is arranged in the substrate scope, thereby constitutes the rigid circuit board of metal substrate penetration heat path.It is the rectangle that is confined to this illustrated example that the shape of circuit board has more than, and can be square, circle, hexagon or other shapes according to the installation needs, on circuit board and metal substrate, also location hole and mounting hole site can be set as required.

Fig. 6 is another embodiment of the utility model, high-thermal conductive metal base printed circuit board and external circuit Pin locations sketch map.Be that with the maximum difference of a last embodiment this circuit board 101 adopts flexible electric circuit board; And overall dimension is different with metal substrate 102; Can be according to installing and outside wiring needs; Extension 601 through flexible electric circuit board is arranged at the substrate outside with circuit pin 501, thereby constitutes a kind of soft or hard bond base circuit board.Extension 601 can be arranged on diverse location and can be designed to difformity according to actual.Therefore; This embodiment has disclosed the printed circuit board (PCB) of the utility model metal substrate penetration heat path can be under the prerequisite that guarantees the vertical heat conductivility of entire circuit plate; Process a kind of soft or hard bond base circuit board; Attractive in appearance and save the demand of outside wiring space to satisfy wiring, be suitable for the lightening design of product.

Fig. 7 is existing metal base printed circuit board stratiform schematic cross-section.Metal substrate 701 1 sides are covered with insulating barrier 702, and copper foil layer 703 is arranged on insulating barrier 702, are used for etched circuit and heat conductive pad 7031, and there is one deck resistance weldering protective layer 704 copper foil layer 703 tops.During application, through soldering layer 705 fixed L ED 706.The heat that LED 706 distributes passes to heat conductive pad 7031 via soldering layer 705, and heat must just can be conveyed to metal substrate 701 through insulating barrier 702 then.In whole heat-transfer path; Soldering layer 705; Copper Foil heat conductive pad 7031 and metal substrate 701 are metal material, and thermal conductivity is preferably arranged, but the thermal conductivity of insulating barrier 702 generally has only about 0.2～2.0W/mK; Become the bottleneck of entire heat dissipation path, cause vertical thermal conductivity of existing whole metal base printed circuit board can only reach 1～4W/mK.

Therefore the utility model is to the existing lower problem of the vertical thermal conductivity of MCPCB; Through improving the manufacture craft of existing metal base printed circuit board; Punch insulating barrier, circuit layer and the resistance weldering protective layer at heat passage position, fill scolding tin conducting heat passage then and directly arrive metal substrate, owing to removed the extremely low insulating barrier of heat passage position thermal conductivity; The heat-transfer path of whole M CPCB directly becomes " soldering layer-metal substrate " by original " metal copper foil-insulating barrier-metal substrate "; Because scolding tin heat conduction thermal conductivity is 50～150W/mK, exceed tens of times than the insulation material, vertical thermal conductivity that can have MCPCB now has significantly lifting.

Though the said embodiment of reference shows especially and has described the utility model, one skilled in the art will appreciate that and can make change to its form and details, and can not break away from the scope of the utility model.Therefore, more than describe the example embodiment that is intended to provide the utility model, and the utility model scope does not receive the restriction of this concrete example that provides.

Claims

1. one kind is passed through heat passage filling scolding tin high-thermal conductive metal base printed circuit board, comprising:

One deck single-clad board is characterized in that: can be rigid circuit board, also can be flexible electric circuit board;

One deck gummed tack coat is positioned at the single-clad board back, it is characterized by the high temperature resistant bonding material;

The layer of metal substrate is characterized in that: fit through the gummed tack coat with the single-clad board back side;

The heat through-hole that at least one fills scolding tin is characterized in that: heat through-hole runs through single-clad board and gummed tack coat; The scolding tin top is the most concordant away from the circuit layer of metal substrate with printed circuit board (PCB), bottom and metal substrate seam.

2. single-clad board according to claim 1; It is characterized in that: said circuit board leave a circle Copper Foil at the heat through-hole perisporium away from the circuit layer of metal substrate can be wetting by soldering flux, under surface tension effects, can make the scolding tin upper surface concordant with this circuit layer with control solder flux amount.

3. single-clad board according to claim 1 is characterized in that: said single-clad board can be lamina, doubling plate even multi-layer sheet.

4. single-clad board according to claim 1 is characterized in that: said big I of single face circuit board shape and metal substrate are in full accord; Also can form soft or hard bond base circuit board with inconsistent the giving prominence to of metal substrate.

5. gummed tack coat according to claim 1 is characterized in that: the gummed tack coat is epoxy jelly membrane, epoxy glass cloth bonding sheet or other resistant to elevated temperatures binding materials.

6. the heat passage of filling scolding tin according to claim 1 is characterized in that: the surface configuration of said scolding tin can be square, rectangle, circle, ellipse or polygon.

7. the heat passage of filling scolding tin according to claim 1 is characterized in that: said scolding tin is alloys such as Sn/Cu, Sn/Ag, Sn/Bi, Sn/Ag/Cu, Sn/Ag/Bi, Sn/Cu/Bi, Sn/Cu/Ni.

8. metal substrate according to claim 1 is characterized in that: said metal substrate material is copper, aluminium, copper alloy, aluminium alloy.

9. metal substrate according to claim 1 is characterized in that: said metal substrate thickness is 0.5mm ~ 3.0mm.